Mobile Phone Touch Screen Controller, Display Driver Chips Become One

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In today’s smartphones, a touch screen has become a must-have function. To implement this function, smartphone makers usually have to use two separate silicon components to fulfill both the touch function and the display driving function, a touch screen controller (TSC) and display driver IC (DDI), respectively. Typically, the TSC silicon supplier and DDI silicon supplier are different semiconductor companies. Most TSC silicon suppliers only supply the TSCs and most DDI silicon suppliers only sell the DDIs. In the smartphone, the TSC is usually mounted on a small PCB and connected to a flex cable. The DDI is typically located behind the front glass plates of the display module. It is always a chip-on-glass part.

TDDI Touch and display integration

However, a new solution for integrating touch and display functions in one chip has been implemented by some silicon suppliers, such as Synaptics, LG Electronics and Focaltech. The main advantages of these touch and display integration (TDDI) chips include cost reduction, a thinner panel, and better performance, which help smartphone makers produce more simply designed, cheaper, and higher performance smartphones.

Chipworks monitors and analyzes the semiconductor industry’s most advanced technologies, including TDDI. Let’s have a closer look at 3 of the earliest mass produced TDDI solution chips, the Synaptics ClearPad, the LG4946 and the LG4945 pictured below.

Synaptics’ ClearPad 4291 TDDI chip

In early 2015, we found Synaptics’ ClearPad 4291 TDDI chip in China’s ZTE Q7 (Blade S6 LUX) smartphone and, since it was the industry’s first commercial mass production TDDI solution used in consumer electronics products, we quickly launched a Basic Functional Analysis (FAR-1503-801) of the chip. Using Inside Technology, a solution that reveals which of today's winning products are taking the hottest components, we can quickly view the genealogical hierarchy of the Synaptics’ die below.

Inside Technology also lets you zero in rapidly on images, reports and schematics for tens of thousands of devices worldwide. Below is a screenshot of the TD4291.

LG4946 and LG4945 TDDI

Chipworks continues to monitor and analyze new generations of TDDI solutions. Early this year, we analyzed the LG Electronics G5 H820 smartphone and, to our surprise, found the LG LG4946 TDDI.

Meanwhile, in the LG Electronics V10 smartphone, we also found a LG LG4945 TDDI. Chipworks suspects that both the LG4946 and LG4945 TDDI devices, with the LG logo on the die markings, might be custom designed for LG Electronics by Korea’s Silicon Works.

Here’s a screenshot comparing the first 2 components.

FocalTech’s TDDI solution

Recently, Chipworks purchased one more smartphones with TDDI: Japan’s Sharp AQUOS U SHV35. In the Sharp AQUOS U SHV35 phone, we found FocalTech’s TDDI solutions. FocalTech calls their solution an integrated driver and controller (IDC). According to FocalTech and other industry sources, the Sharp SHV35 is equipped with the FT8606.

Chipworks expects that these TDDI chips will be adopted by more and more smartphone makers in the near future and will continue to report on new devices and technologies in this field. Please contact us regarding any upcoming TDDI Basic Functional Analysis reports.